Unit 5

   Work is force times distance (work=fxd). It can only occur when parallel, like a person picking up a cat up off the ground. If the person walked forward while holding the cat, work would not occur. Work is measured in joules.
   Power is work divided by time (power=work/time). Power is measured in watts and unlike work, which is required for power, requires time.
   Work is related to Kinetic energy because work= a change in kinetic energy. A change in kinetic energy = KEfinal-KEintitial. Kinetic energy = 1/2 m v ^2.
   There are three types of simple machines: ramps, levers, and pulleys. A simple machine decreases the amount of force needed by increasing the distance covered. For example, someone could pick a very heavy cat up off the ground, or they could push it up the ramp. Picking it straight up would require a large amount of force, but a short distance, but pushing it up the ramp would require much less force because it would be a longer distance.
   This happens because of conservation of energy. This means that the work in has to equal the work out. In the case of machines this trade of distance and force looks like this: fD=Fd. This concept can also be applied to a pendulum or a roller coaster. As far as a pendulum is pulled to one side, it will never get higher than that and a roller coasters hills can never be greater than the first one.
  This is because of potential and kinetic energy. Potential energy = mass x gravity x height. PE does not require motion, just height. When something is at the top of a fall, it has a certain amount of PE and no KE and at the very end of a fall it has no PE and a certain amount of KE.